Detergent compositions containing acyl dicyandiamide tarnish inhibitors



DETERGENT COMPOSiTIONS CONTAINING ACYL DICYANDIAMIDE TH INHBITORS Alan Dalton Scott, Bebington,

Brothers Company, Maine England, assignor to Lever New York, N. Y., a corporation of No Drawing. Application September 8, 1954, Serial No. 454,841

This invention relates to cleaning compositions containing tarnish inhibitors and more particularly to polyphosphate and synthetic detergent compositions containing acyl dicyandiamides as tarnish inhibitors.

Compositions containing polyphosphates and/or synthetic detergents are now widely used for detergent and other purposes. Aqueous solutions of polyphosphates and some synthetic detergents tend when at certain pH values to tarnish copper, and nickel and copper alloys such as German silver (a nickel-zinc-copper alloy) to a variety of shades from yellow to bluish black, especially if the solutions are at elevated temperatures and are allowed to remain in contact with the metal for several minutes. Since German silver is frequently used for household articles commonly washed in polyphosphatebuilt detergent compositions, it is evident that this is a serious problem.

In accordance with the instant invention polyphosphate and detergent compositions are provided containing a tarnish inhibitor which compositions have a reduced tendency to tarnish copper, and nickel and copper alloys such as German silver. The tarnish inhibitor of the invention is an acyl dicyandiamide which is described by the following general formula:

RtiiNH( J-NHON R is an aliphatic hydrocarbon group having either a straight or branched chain and can be saturated or unsaturated. The number of carbon atoms in the R chain is not critical. Optimum tarnish inhibiting properties are displayed by compounds in which R has from eleven to seventeen carbon atoms.

Typical R radicals having straight and branched chains are methyl, n-heptyl, n-octyl, tert-octyl, nonyl, decyl, undecyl, 2-ethyl decyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, decynyl, dodecenyl, octa decenyl, octadecadienyl and dodecynyl.

The following acyl dicyandiamides are exemplary:

Many of the acyl dicyandiamides are known compounds. They are readily prepared by reaction of dicyandiamide and the corresponding acyl chloride in the presence of alkali, such as potassium hydroxide. The

2,813,831 Patented Nov. 19, 1957 acyl dicyandiamides are non-toxic, sparingly water-soluble substances, sufiiciently water-soluble to permit their incorporation in polyphosphate and synthetic detergent solutions in the amounts required to impart tarnish inhibition thereto.

An amount of acyl dicyandiamide would be added to the polyphosphate and/or synthetic detergent composition sufiicient to give tarnish inhibition when the composition is used in its normal way, say, at a washing concentration. Usually about 0.5% of the acyl dicyandiamide gives adequate tarnish inhibition, but larger amounts can be used if desired. An amount of from 0.5 to 5% is effective under nearly all conditions and therefore is pre ferred. The maximum amount of acyl dicyandiamide is not critical but more than is necessary to give the desired effect usually would not be used, and of course an amount in excess of that soluble in the use solution would not be used. It will be understood that the amount required will depend in part upon the tarnish-inhibiting properties of the particular acyl dicyandiamide in question, upon the tendency of the polyphosphate and/ or synthetic detergent with which it is used to tarnish copper and nickel and copper alloys, and upon the amounts of polyphosphate and synthetic detergent present.

The tarnish inhibitors of the invention are effective with water-soluble polyphosphates as a class at pH values where such polyphosphates tend to tarnish German silver (usually pH 6 or above) and particularly those polyphosphates identified by the following general formula from which it is seen that both the acids and their various salts are contemplated:

where M1, M2 and Ms are hydrogen or an alkali metal, such as sodium potassium and ammonium, and can be the same or different, and M is M1 and/ or M2 and/ or Ma, a is an integer of 1 or more, usually 1 to 4, b is an integer of 1 or more, usually 1 or 2, x is an integer of 1 or more, usually 1 to 6. In the case where a is 2, b is l and x is l, the compound is a pyrophosphate. When a is 1, b is 1 and x is l, the compound is a metaphosphate. Others will be evident to those skilled in the art.

The upper limit of a, b and x is not critical, but will be determined by the increasingly lower water-solubility as molecular weight increases. The sodium polyphosphates are preferred.

As the general formula shows, both the normal and acid salts of the phosphates are within the scope of the invention.

Among the polyphosphoric acids and their alkali metal salts coming within the invention are the polymetaphosphoric acids (HPOa)x(a is l, b is 1, x is more than 1), pyrophosphoric acid H4P2O7 (a is 2, b is l, x is l), triphosphoric acid H5P301o (a is 3, b is 2, x is 1), and tetraphosphoric acid H6P4013 (a is 4, b is 3, x is l). NasPsOro, K4P2O7, NarPzOv, NazHzPzo'z, Na6P401a, Sodium Polyphos (NarzPmOar-Blockson),

K4(PO3)4.2H2O Pascals salt, sodium dimetaphosphate, sodium tn'metaphosphate (Knorres salt), sodium tetrametaphosphate and sodium hexametaphosphate (Grahams salt) are examples.

The acyl dicyandiamide tarnish inhibitors can be incorporated in compositions containing polyphosphates, and in compositions containing synthetic detergents, and are efiective to reduce tarnish due to polyphosphate or detergent in each of these types of compositions. Such compositions are marketed in solid form, e. g. as powders, chips or flakes, or in liquid form, e. g. as solutions. The physical form of the composition is not critical.

The tarnish inhibitors are particularly useful in synthetic detergent compositions which contain one or more polyphosphates as builders and one or more synthetic detergents, i. e., anionic detergents, nonionic detergents, and mixtures thereof. In many instances they display an enhanced tarnish-inhibiting action in the presence of both polyphosphate and detergent.

. The polyphosphate-built detergent compositions should contain conventional proportions of active detergent, usually within the range between 5 to 40%, polyphosphate in any amount, usually between 5 to 50%, based on the total composition, and the residue builders and inert materials.

The acyl dicyandiamides 'are not compatible with cationic detergents and display very poor tarnish-inhibiting action in their presence.

The acyl dicyandiamides are useful with a wide variety of anionic and nonionic synthetic detergents, with and without polyphosphates.

The alkyl aryl 'sulfonates are a class of detergents well known in the art under this name. Examples are the sulfonated phenylpolypropylene alkanes, characterized by the branched chain structure of polypropylene and a tertiary alkyl carbon at the benzene ring, and having the following general structure:

where M is hydrogen, an alkali metal or an organic amine cation, and R1 and R2 are alkyl, of the type formula C I-I2,,+l, and at least one R is a polypropylene grou the whole alkyl group containing preferably twelve to fifteen carbon atoms. These are known compounds, whose preparation and properties are set forth in U. S. Patent No. 2,477,383 to Lewis, issued July 26, 1949; they are available in commerce under the trade names Oronite, ultrawet and Neolene.

Another class of useful detergents are the amidoalkane sulfonates which are characterized by the following structure:

where A is hydrogen or an alkali metal, i. e., ammonium, sodium, or potassium, n is a small whole number from one to about five, preferably two or three, R is hydrogen, or an alkyl, aryl, or cycloaliphatic group, such as methyl, and R is an alkyl or alkylene radical, such as myristyl, palmityl, oleyl and stearyl; Sodium palmitic tauride, sodiumpalmitic methyl tauride, sodium myristic methyl tauride, sodium palmitic-stearic methyl tauride and sodium palmitic methyl amidopropane sulfonate have been found to be particularly suitable for use in the compositions of the invention.

These compounds are prepared by interacting the corresponding aliphatic acid anhydride or halide with an or ganic aliphatic aminosulfonic acid, such as taurine, NHzCHzCHzSOsl-I, and the various N-substituted taurines, such as N-methyl taurine, or aminopropane sulfonic acid, NH2(CH2)3SO3H.

The invention is also applicable to other water-soluble alkyl aromatic sulfonic acids, such as those prepared by alkylating benzene or naphthalene with a kerosene fraction followed by sulfonation to aliphatic sulfonic acids, esters of sulfuric acid with aliphatic alcohols of ten to eighteen carbon atoms, particularly those derived by the reduction of coconut oil, palm oil and like long-chain fatty acids, sulfonated castor oil, esters and 'ethers of isethionic acid, long-chain fatty acid esters and long-chain alkyl ethers of 1,2-dihydroxy propane-B-sulfonic acid and sulfuric acid esters of mono-glycerides and glycerol monoethers. The salts of these acids are ordinarily employed.

The tarnish inhibitors are also useful with nonionic detergents, such as, for example, dialkanolamidcs, and the alkyl oxyether and ester and thioether and ester detergents having the following general formula:

where R is a straight orbranched chain saturated or unsaturated hydrocarbon group having from eight to eighteen carbon atoms or an aralkyl group having a straight or branched saturated or unsaturated hydrocarbon group of from eight to eighteen carbon atoms attached to the aryl nucleus, and attached to A through the aryl nucleus, A is selected from the group consisting of ethereal oxygen and sulfur, carboxylic ester and thiocarboxylic ester groups and x is a number from eight to twenty. R can for example be a straight or branched chain octyl, nonyl, decyl, lauryl, myristyl, cetyl or stearyl group, or an alkyl aryl group such as octylbenzene, nonylbenzene, decylbenzene, st earyl benzene, etc.

The sulfated ethoxynated derivatives of the above also are useful anionic detergents:

where M is hydrogen or an alkali metal or organic amine cation and x, A and R are as above.

When R is alkyl it will be evident the. the detergent can be regarded as derived from an alcohol, mercaptan, oxy or thio fatty acid of high molecular weight, by condensation with ethylene oxide. Typical of this type of alkyl ether are the condensation products of oleyl or dodecyl alcohol or mercaptan with from eight to seventeen moles of ethylene oxide, such as Emulfor ON," Nonic 218, Sterox SE and Sterox SK. Typical alkyl esters are 61226 and Renex (polyoxyethylene ester of tall oil acids), Sterox CD and Neutronyx 330" and 331 (higher fatty acid esters of polyethylene glycol).

When R is aralkyl, the detergent can be derived from an alkyl phenol or thiophenol.

The ethoxynated alkyl phenols and thiophenols have the following general formula:

A(oH2oHro)=oH20H,oH where R is a straight or branched saturated or unsaturated hydrocarbon group having at least eight carbon atoms up to approximately eighteen carbon atoms, A is oxygen or sulfur and x is a number from eight to twenty. R can, for example, be a straight or branched chain octyl, nonyl, decyl, lauryl, cetyl, myristyl or stearyl group. Typical are the condensation products of octyl and nonyl phenol and thio-phenol with from eight to seventeen moles of ethylene oxide, available commercially under the trade names NlW, Antarox A-400, Igepal CA and CO, Triton X-lOD, Neutronyx 600 and fTergitol NFX.

The detergent composition can contain supplemental builders including alkali metal and alkaline earth metal sulfates, chlorides, silicates, borates, carbonates, metaphosphates, and orthophosphates, such as sodium silicate, magnesium sulfate, sodium tetraborate, sodium carbonate, sodium sulfate, trisodium phosphate, potassium carbonate, disodium orthophosphate, sodium rnetaphosphate, calcium sulfate, calcium chloride, sodium chloride, sodium borate and potassium metaphosphate.

In addition to or instead of the above-mentioned supplemental inorganic salts, organic materials such as starch, polyethylene glycols, polyvinyl alcohols and salts of carboxymethylcellulose can be used as builders. It has been found that between about 0.1 and 1% of an alkali metal carboxymethylcellulose increases detergency and sudsing.

The builder mixture is so'chosen among alkaline, neutral andacidic salts that the composition obtained in an aqueous 0.14% solution has a pH of 7 or above. Preferably, its pH lies within the range from 7 to about 10 since solutions which are more alkaline may be irritating to the skin and tend to weaken some fabrics, particularly woolens. In general, the alkali metal carbonates are preferred agents for bringing the pH of the solution to a high alkaline value within the preferred range.

The detergent composition is prepared by conventional methods, as by blending the ingredients thereof in an aqueous solution or slurry and then drying the resulting mixture in a spray or drum dryer at elevated temperatures.

The pure tarnish inhibitors may be added to the polyphosphate or detergent composition at any stage of its manufacture, to the finished polyphosphate or detergent composition, or to the polyphosphate or detergent solution.

If a crude preparation is to be used, it is preferred to incorporate it direct in the solution, since processing, such as spray drying, may adversely affect the tarnish-inhibiting properties of such crude preparations.

In the examples the tarnishing action of the compositions was evaluated by this test:

Five grams (dry solids basis) of the composition to be tested is dissolved in one quart of distilled water and 300 ml. of the test solution placed in a suitable container and brought to 160 F. A strip of German silver metal is polished with a metal polish, washed and dried, placed in the solution and the solution held at 160 to 170 F. for one half hour. The effectiveness of the inhibitor is rated as follows:

Excellent=perfect protection or barely noticeable cast Good=very slight attack Moderate=slight attack Poor=badly tarnished Tarn=severe tarnish The acyl dicyandiamides used in Examples 1 to 6 and 11 to 17 were prepared as follows:

Dicyandiamide, 105 g. (1.25 moles) was mixed with 112 g. two moles) of potassium hydroxide in 900 cc. of acetone while the temperature was kept at 10 C. for one hour. To this solution there was slowly added 219 g. (one mole) of lauroyl chloride at a temperature below 10 C. The reaction mixture was diluted with 3 liters of water and then acidified with acetic acid. The precipitate of the crude acyl dicyandiamide was filtered and washed with acetone to remove the fatty acid. An aqueous washing removed the water-soluble impurities.

The myristoyl and stearoyl dicyandiamides were prepared in an identical manner, using the same molar proportions as employed in the preparation of the lauroyl dicyandiamide.

The acyl dicyandiamides used in Examples 7 to 10 were crude products from a modified method of preparation in which water was substituted for the acetone and no attempt was made to purify the reaction product.

EXAMPLES 1 TO 3 Detergent compositions were prepared having the following formulation:

(Acyl dicyandiamide added later (see below)--0.39 to 0.79% based on the combined weight of the polyphosphates and detergent in composition.)

To solutions of these compositions in distilled water for testing for tarnish inhibition were added the acyl dicyandiamides listed in the table in the amount indicated Table I Grading at; Concentration of Tarnish Inhibitor Example No. Tarnish Inhibitor None 0.39% 0.79%

1 Lauroyl dioyandiamide Tarn Poor Excellent. 2 Myristoyl dicyandiamide. do Good Do. 3 Stearoyl dicyandiamide. do do Do.

The myristoyl and stearoyl dicyandiamides are the most effective; the lauroyl dicyandiamide is elfective at a 0.79% concentration.

EXAMPLES 4 TO 6 A slurry was prepared of the following formulationi Suflicient water was added to To the slurry was added 0.5% by weight of the composition (0.79% by weight of the detergent and polyphosphate) of one of the acyl dicyandiamides listed in the table below. The mixture was agitated at F. to obtain a smooth slurry and then drum dried. The composition then was evaluated for tarnishing action by the test with the following results:

provide 40% in the slurry.

Table II Grading at Concentration of Tarnish Inhib- Example No. Tarnish Inhibitor itor None 0.79%

Lauroyl dicyandiamide. Tarn Moderate. Myristoyl dieyandiamide d0 Excellent. Stearoyl dicyandiamide. .-.d0 Do.

The myristoyl and stearoyl dicyandiamides are the most efiective of those tested. The lauroyl dicyandiamide is elfective at higher concentrations.

EXAMPLES 7 AND 8 The detergent composition of Examples 1 to 3 was used with a crude acyl dicyandiamide product obtained according to the modified procedure in which water was substituted for the acetone and no attempt was made to purify the reaction product. The compositions were tested in solution form with the following results:

When the.crude material is employed the lauroyl .de rivative" is the mo'st eifective.

EXAMPLE 9 Aqueous (distilled water) detergent composition solutions were preparedhaving the following-formulation:

Table V Grams-per Quart Example No 10 -11 12 i 13 14 15 Stet-ox CD active 1 0.9 0.9 Sodium Oronite active 0. 9 0. 9 Tetrasodium pyrophosphate s Lauroyl dicyandiamide Stearoyl dicyandiamide 0. 025 pH adjusted to 9. 5 9. 5 9; 5 7. 5 Grading in tarnich test. Good Tarn Exc Good Mod -Exc.

Condensation product of tall oil fatty acids with 8-to' 10-moles of ethylene oxide.

' See-Examples 1- to 3.

Example 10 shows thata' solution of Sterox CD has a slight' tarnishing'efiect. In thepresenceof tetrasodium pyrophosphate the tarnishing is increased (Example 11). Example 12 shows that in the presence of both the Sterox CD and the tetrasodiumpyrophosphate, 0.79%; (by-weight of detergent andpyrophosphate) stearoyl' dicyandiamide is capable of overcoming the tarnishing effect ofboth the pyrophosphate and the detergent. It of course follows from Example: 12 that the stearoyl dicyandiamide also would overcome the tarnishing effect of eitheralone, so such solutions were =n'ot1tested.

Example 13 shows that lauroyl dicyandiamide is effective in overcoming the tarnishing etfect of the tetrasodium pyrophosphate (cf. Example 11).

Example 14 shows that sodium Oronite has a slight tarnishingettect, 'and Example 15 shows that in the presence of stearoyl dicyandiamidetthis tarnishing effect is'completely overcome. A pH of 7 .5 was selected in Examples 14 and 15 because it approximates the pH of light "duty polyphosphate-free detergents and is a pH atwhich sodium Oronite discolors German silver.

Compositions containing tarnish inhibitors of the invention have a reduced tendency to tarnish copper, nickelcopper zinc alloys such as German silver, coinage nickel or brassuwhich normally tarnish when exposed to aqueous solutions containing polyphosphates and/ or syntheticdetergents. It is not possible at .thistime to explain why the compounds of the invention are effective tarnishinhibitors. However, 'it has been observed thatwhen a German silver utensil is'immersed for a'period in an inhibitorand polyphosphate-containing detergent solution, and then immersed in a p0lyphosphatewontaining detergent solution not containing inhibitor, only slight tarnishing results. "This is taken as an indication thatthe inhibitor is preferentially adsorbed by the metal, and that this is important in tarnish prevention, but of course .such evidence is not conclusive.

" *Obviously; many: modifications andvariations may be made in the invention herein set forth without departing fromv thelspirit and scope thereof, and only such limitations shouldrber imposed as are indicated inithe appended claims.

All parts and. percentages .inzthe specification and. claims are by weight. Proportions of acyldicyandiamide are based on the weight of.tl1e tarnish-producing substance,

i.i e; polyphosphate and/or detergent; inthe examples,

when fbtithjpblyphosphate and' detergent werepresent,

the weights: of acyh'dicyandiamides 'werefib'ased" on the total ofibdth wei'ghts.

I'cl'a'im:

1. A1 detergent composition consistingiessentially of a water 'soluble inorganic polyphosphatewhich in aqueous solution tarnishes copper and copper and nickel alloys and: a compound'having tarnishinhibitingproperties and defined byfthe general formula:

R-F-NH-C-NHCN ZNH where R -is an" aliphatic" hydrocarbon radicalythe said compound being' in an'- amount to lessen the tarnishing action of thepolyphos'phate.

2. A detergent composition in accordance with claim 1 in which the tarnishing inhibitor is 'lauroyl-dicyandiamide.

I 3. *Adetergent' composition in accordance with claim 1 inwhichthe tarnishinhibitor is myristoyl dicyandiamide.

. 4. A detergentcomposition in accordance with'claim l inwhich the tarnish inhibitor :is stearoyl dicyandiamide.

5. A nonsoap detergent composition consisting essentially of-an. active organic nonsoap detergent selected from*the group consisting of'anionic and nonionic synthetic detergents whichin aqueous 'solution tarnishes copper andv copper andnickel alloys and a compound having tarnish-inhibiting properties and defined by the general. formula:

where R is an aliphatic hydrocarbon radical, the said compound being in an amount to-lessen thetarnishing action of the detergent.

6. A detergent composition in accordance with claim 5 in which the .tarnish inhibitor is lauroyl dicyandiamide.

7. A'detergent composition in accordance with claim 5 in whichthe tarnish inhibitor'is' myristoyl dicyandiamide.

8. Adeterge'nt composition inaccordance with claim 5 in whiclr'the tarnish inhibitor is stearoyl: dicyandiamide. 9. -A detergentcomposition in accordance'with claim5 in"whieh' the detergent is sodium 'phenylpolypropylene sulfon'ate,

110."A'detergent compositionin accordance with claim 5 in which the"detergent"ista' condensation product of tall oil fatty acids 'and' 8 "to 10 moles of ethylene oxide.

11;"A *nonsoap detergent composition. consisting es- 'scntially ofan" active organic nonsoap detergent selected from'the group" consisting of anionic and nonionic syn- 'thetic'detergents, a water-soluble inorganic polyphosphate which in aqueous solution tarnishes copper and copper and nickel alloys and a compound. having tarnish inhibiting properties and defined bythe' general formula:

where R is an aliphatic hydrocarbon radical, the said compoundbeing-inian amount-.tolessen the tarnishing action of the polyphosphate.

12. A detergent composition in accordance with claim 11 in'which the tarnish inhibitor is lauroyl dicyandiamide.

13. A detergent-composition inaccordance with claim 11 in' which the tarnish" inhibitor is myristoylidicyandiamide.

14. A detergent composition in accordance with claim 11 in- 'whichthe tarnish inhibitoris stearoyl. dicyandiamide.

"'15 A detergent-composition in :accordance with claim 1 1 in which-thepolyphosphate is a'tripolyphosphate 16;A detergent composition in accordance with claim 11 in which the polyphosphate is a pyrophosphate.

17. A detergent composition consisting essentially of a Water-soluble"substance;selected from their, group cou- 9 sisting of inorganic polyphosphates and anionic and nonionic synthetic nonsoap detergents which in aqueous solution tarnish copper and copper and nickel alloys and a compound having tarnish inhibiting properties and defined by the general formula: 5

R-fJ-NH-fl-NHGN where R is an aliphatic hydrocarbon radical, the said compound being in an amount to lessen the tarnishing 10 action of the substance.

18. A detergent composition in accordance with claim 17 in which Rhas from eleven to seventeen carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF A WATER-SOLUBLE INORGANIC POLYPHOSPHATE WHICH IN AQUEOUS SOLUTION TARNISHES COPPER AND COPPER AND NICKEL ALLOYS AND A COMPOUND HAVING TARNISH INHIBITING PROPERTIES AND DEFINED BY THE GENERAL FORMULA:
 5. A NONSOAP DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF AN ACTIVE ORGANIC NONSOAP DETERGENT SELECTED FROM THE GROUP CONSISTING OF ANIONIC AND NONIONIC SYNTHETIC DETERGENTS WHICH IN AQUEOUS SOLUTION TARNISHES COPPER AND COPPER AND NICKEL ALLOYS AND A COMPOUND HAVING TARNISH INHIBITING PROPERTIES AND DEFINED BY THE GENERAL FORMULA: 